/*
 * Copyright (c) 2004-2022, University of Oslo
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * Neither the name of the HISP project nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.hisp.dhis.webapi.controller.dataitem.helper;

import static lombok.AccessLevel.PRIVATE;
import static org.apache.commons.collections4.CollectionUtils.isNotEmpty;
import static org.springframework.util.Assert.state;

import java.util.List;
import lombok.NoArgsConstructor;
import org.hisp.dhis.common.Pager;
import org.hisp.dhis.dataitem.DataItem;
import org.hisp.dhis.webapi.webdomain.WebOptions;
import org.springframework.jdbc.core.namedparam.MapSqlParameterSource;

/**
 * Helper class responsible for providing pagination capabilities on top of data item objects.
 *
 * @author maikel arabori
 */
@NoArgsConstructor(access = PRIVATE)
public class PaginationHelper {
  /**
   * This method will "paginate" the given list based on the given options and return only the
   * elements present in the pagination window.
   *
   * @param options
   * @param itemViewObjects
   * @return the list of "paginated" items
   */
  public static List<DataItem> paginate(WebOptions options, List<DataItem> itemViewObjects) {
    state(options.getPage() > 0, "Current page must be greater than zero.");
    state(options.getPageSize() > 0, "Page size must be greater than zero.");

    if (options.hasPaging() && isNotEmpty(itemViewObjects)) {
      // Pagination input.
      int currentPage = options.getPage();
      int totalOfElements = itemViewObjects.size();
      int maxElementsPerPage = options.getPageSize();

      Pager pager = new Pager(currentPage, totalOfElements, maxElementsPerPage);

      int currentElementIndex = pager.getOffset();
      boolean hasMorePages = (totalOfElements - currentElementIndex) > pager.getPageSize();

      if (hasMorePages) {
        int nextElementsWindow = pager.getPageSize() * pager.getPage();
        itemViewObjects = itemViewObjects.subList(currentElementIndex, nextElementsWindow);
      } else {
        // This is the last page.
        itemViewObjects = itemViewObjects.subList(pager.getOffset(), totalOfElements);
      }
    }

    return itemViewObjects;
  }

  /**
   * Sets the limit of items to be fetched IF paging is enabled. The max limit is set into the
   * paramsMap.
   *
   * @param options the source of pagination params
   * @param paramsMap the map that will receive the max limit param (maxLimit)
   */
  public static void setMaxResultsWhenPaging(WebOptions options, MapSqlParameterSource paramsMap) {
    if (options.hasPaging()) {
      int maxLimit = options.getPage() * options.getPageSize();
      paramsMap.addValue("maxLimit", maxLimit);
    }
  }
}
